Ignition Quality Parameters of Slow Speed Diesel Engine

Ignition quality parameters:

Energy

Viscosity

Maximum firing pressure.
4. Injection delay
5. Ignition delay .

1. Energy comparison

• The injection pump is a volumetric pump
• The higher the density the more energy it contains per volume unit
• The density difference between HFO and MDO is larger than the difference in net calorific value

2. Viscosity comparison

The viscosity of MDO is lower than the viscosity of HFO (even HFO is heated)
• Lower viscosity fuels result in more internal leakage in the injection pump from the high pressure side to low pressure side.
• Internal leakage has to be compensated by giving more fuel rack

3. Maximum firing pressure

Dependent on the charge air pressure
• To achieve proper combustion, the firing pressure has to be high and thus also the charge air pressure
• Timing of the fuel pump

4. Injection delay

Injection delay is the time it takes to build up a pressure higher than the opening pressure of the nozzle.
• Normally 4…5 ° of crank angle
• The delay is comparable to the condition of injection equipment

5. Ignition delay

is the time gap between the commencement of injection and the commencement of ignition.

Dependent on the fuel quality

Compression temperature has a big influence on the ignition delay

Compression temperature is not high enough for the fuel to ignite longer ignition delay

Source: Wartsila

Besides consider the following for better ignition quality of slow speed diesel engine: